A wind power generation system generates electric power by utilizing wind power energy which is renewable energy.
In the wind power generation system, a separated flow may occur on a surface of a windmill blade, causing a fluctuation of power generation amount. For example, when a wind speed and a wind direction fluctuate suddenly, the velocity triangle around windmill blades deviates largely from a rating point, and thus the separated flow occurs in a wide range. It is not possible to respond sufficiently to rapid fluctuations of wind speed and wind direction by adjustment of yaw angle or pitch angle. Accordingly, in the wind power generation system, there may be cases where it is difficult to maintain power generation output stably and it is uneasy to increase efficiency.
As a measure for this, it has been proposed to dispose an airflow generation device on the surface of a windmill blade to generate a plasma airflow, thereby suppressing occurrence of separated flow. Further, it has been proposed to dispose a plurality of airflow generation devices in a blade span direction and control the plurality of airflow generation devices according to the separated flow which differs depending on a position in a radial direction of a rotor.
When the airflow generation device is disposed on the surface of a windmill blade, a step may be formed on the surface of the windmill blade by the airflow generation device. Thus, there may be cases where a flow around the windmill blade is disturbed, making it uneasy to maintain power generation output stably.
When the plurality of airflow generation devices are laid side by side in the blade span direction on a windmill blade having a long span length, it is necessary to connect connection conducting wires to each of the plurality of airflow generation devices. The connection conducting wires are high-voltage wires and thick, and thus there may be cases where a flow is disturbed around the windmill blade by a step due to the connection conducting wires, and it is not possible to maintain power generation output stably.
When the airflow generation devices are retrofitted to windmill blades in an already built wind power generation system in particular, there may be cases where modification of the windmill blades are not allowed for securing characteristics such as strength. For example, it may be not allowed to cut away part of the surface of a windmill blade and fit the airflow generation devices in the cut part, or bore a hole in the windmill blade to place connection conducting wires through this hole. Accordingly, as described above, a step is formed on the surface of the windmill blade, which can make it more difficult to maintain power generation output stably and uneasy to improve efficiency.